Sponge

Aplysilla rosea (Barrois, 1876)

Taxonomy

Scientific Details

Species of Aplysilla occur world-wide in water ranging from very shallow to over 600 m deep. Easily confused with other encrusting genera in this family, they can really only be identified using features visible under the microscope.

Family level characters:The fibre skeleton of sponges in this family is always branching (dendritic), never mesh-like (reticulate). Darwinellid sponges are generally encrusting in habit but can be erect and branching. Of the four genera in this family, three are included here.

Order level characters:Sponges of this collagenous order also lack spicules. They are often soft and very fragile due to a reduction in the fibrous skeleton in relation to the tissue mass. All begin their growth from a base that spreads over the substrate. The fibres of the skeleton then grow either in a branching, tree-like (dendritic) fashion (Family Darwinellidae), or adopt a mesh-like (reticulate) growth pattern (Family Dictyodendrillidae). The fibres of all sponges in this order show strong, concentric layering (lamination) and a very pronounced central core (pith), visible microscopically as a dark, opaque central line or region of collagen within the fibre. Examples of both families occur in southern Australian waters but only one family is included here.